CVE-2024-40956 in Linux
Summary
by MITRE • 07/12/2024
In the Linux kernel, the following vulnerability has been resolved:
dmaengine: idxd: Fix possible Use-After-Free in irq_process_work_list
Use list_for_each_entry_safe() to allow iterating through the list and deleting the entry in the iteration process. The descriptor is freed via idxd_desc_complete() and there's a slight chance may cause issue for the list iterator when the descriptor is reused by another thread without it being deleted from the list.
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Analysis
by VulDB Data Team • 09/30/2024
The vulnerability identified as CVE-2024-40956 resides within the Linux kernel's dmaengine subsystem, specifically affecting the Intel Data Plane Engine (IDXD) driver implementation. This flaw manifests as a potential use-after-free condition during interrupt processing operations, creating a critical security risk that could be exploited to compromise system integrity. The issue occurs in the irq_process_work_list function where the driver handles descriptor processing for DMA operations, making it particularly dangerous in environments relying heavily on high-performance data processing capabilities.
The technical root cause stems from improper list iteration mechanisms within the kernel's device driver code. The original implementation failed to utilize the safe list iteration pattern provided by list_for_each_entry_safe(), which is specifically designed to handle scenarios where list entries may be removed during iteration. When the idxd_desc_complete() function executes to free a descriptor, the standard list_for_each_entry() macro can encounter undefined behavior if another thread attempts to reuse the same memory location before the iteration completes. This creates a race condition where the iterator may reference freed memory or access invalid list pointers, potentially leading to system crashes or arbitrary code execution.
The operational impact of this vulnerability extends beyond simple system instability, as it represents a fundamental flaw in the kernel's memory management and concurrency handling for high-speed data processing operations. Attackers could exploit this condition to cause denial of service through system crashes or potentially escalate privileges by leveraging the memory corruption to execute malicious code within kernel space. The vulnerability affects systems utilizing Intel IDXD hardware accelerators, particularly those implementing DMA operations for high-throughput networking, storage, or computing applications where the driver's interrupt handling is frequently invoked.
Mitigation strategies should prioritize immediate deployment of kernel updates containing the patched implementation that properly employs list_for_each_entry_safe() for all descriptor list iterations. System administrators must also implement comprehensive monitoring for unusual interrupt processing patterns or system instability that might indicate exploitation attempts. The fix aligns with established security best practices and addresses the underlying CWE-415 vulnerability category related to double free conditions and memory management errors. Organizations should consider implementing additional runtime protections such as kernel address space layout randomization and memory corruption detection mechanisms to further reduce the attack surface. The patch demonstrates proper adherence to kernel development standards and represents a critical security enhancement that prevents the exploitation of concurrent access patterns in device driver code.